@PixelGeek I don't think this was the issue.
@Daniel_Remes Once your modal is created you can set it's top value depends on the browser height. You can do that using the following script wchich you should put in the Custom Code in
before </body> in site settings.
If you have followed @thesergie tutorial provided here also by @PixelGeek you should find following line of code:
$('.modal-background').fadeIn(); and above it write something like this:
$('.modal-window').css('top', $(window).height()/2 - $('.modal-window').height()/2);
Things are getting different if you want to create a full responsive modal window. This one might be easier to hire a freelancer for that if you are not familiar with coding.
I'm not sure about the second question. I'll try to find a way for that. Remind me please with email about that. Detaisl are in my profile.